ABSTRACT
BACKGROUND: Cerebral cavernous malformation (CCM) in third ventricular area may become symptomatic relatively rarely, secondary to hemorrhage and growth or rupture into the ventricle, causing obstructive hydrocephalus, during third trimester of pregnancy. CASE DESCRIPTION: A 34+4 weeks pregnant (G4P1A2) lady was admitted to one of our satellite hospitals with one-week history of severe headache, blurred vision, nausea, vomiting, and right-sided facial numbness. At presentation, she had sudden decreased level of consciousness with Glasgow Coma Scale (GCS) equal to 4, and bilateral fixed pupils. A brain computed tomography (CT) showed enlargement of both lateral ventricles with 2.5cm sized round hemorrhagic lesion at the right posterior thalamic region. After medical stabilization and placement of an external ventricular drain (EVD), the patient was referred for neurosurgical intervention. Magnetic resonance imaging (MRI) revealed a cavernous hemangioma adjacent to the right posterior wall of the third ventricle. After cesarean section and anterior interhemispheric trans-callosal approach, the mass was removed totally. However, on third postoperative day, she experienced mild hypoxia and dyspnea with fever. Chest CT-scan of the patient showed bilateral consolidation. Thereafter, COVID-19 was confirmed subsequently with positive nasopharyngeal swab testing for RT-PCR. The patient was treated as COVID-19 infection and symptoms improved on day 10 of the treatment and completely recovered. CONCLUSIONS: COVID-19 may promote ICH from CCM leading to obstructive hydrocephalous in our patient.
Subject(s)
COVID-19 , Third Ventricle , Cesarean Section , Female , Humans , Pregnancy , Pregnant Women , SARS-CoV-2ABSTRACT
BACKGROUND: Limitation of active cervical range of motion as a sequel of both spinal instrumentation and neurological injury may occur after Cervical Spinal Cord Injury (CSCI) surgery. The majority of tasks performed in daily life require a minimum of Active Cervical Range of Motion (ACROM). The aim of this study was to report ACROM in patients with subaxial CSCI, and in a control group with asymptomatic cervical spine. METHODS: A cross-sectional study was performed in 46 cases of traumatic complete motor CSCI and 41 asymptomatic cases. Patients underwent quantitative measurement of ACROM on six movements, using an analogue inclinometer, and rehabilitation status assessment on the Spinal Cord Independence Measure (SCIM) III. RESULTS: Forty-six CSCI cases and 41 asymptomatic controls were included. Mean flexion, extension, rotation, and lateral inclination were significantly lower in the CSCI group than in controls (P<0.0001). SCIMIII self-care subscores in the CSCI group showed significant correlation with mean cervical rotation (correlation coefficient, +0.508, P=0.0003). Regression analysis on mean ACROM in the CSCI group, yielded significant a negative correlation with age (P=0.037). CONCLUSIONS: CSCI significantly affected ACROM. Also, restriction of cervical rotation had significant negative correlation with SCIM-III self-care subscores.
Subject(s)
Cervical Cord/injuries , Cervical Vertebrae/injuries , Spinal Cord Injuries/rehabilitation , Activities of Daily Living , Adult , Age Factors , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Rotation , Self Care , Treatment OutcomeABSTRACT
This corrects the article DOI: 10.1038/sc.2016.7.
ABSTRACT
We propose an entanglement classification for symmetric quantum states based on their diagonal matrix-product-state (MPS) representation. The proposed classification, which preserves the stochastic local operation assisted with classical communication (SLOCC) criterion, relates entanglement families to the interaction length of Hamiltonians. In this manner, we establish a connection between entanglement classification and condensed matter models from a quantum information perspective. Moreover, we introduce a scalable nesting property for the proposed entanglement classification, in which the families for N parties carry over to the N + 1 case. Finally, using techniques from algebraic geometry, we prove that the minimal nontrivial interaction length n for any symmetric state is bounded by .
ABSTRACT
STUDY DESIGN: A cross-sectional study. OBJECTIVES: This study was performed for epidemiological assessment of Iranian Traumatic Spinal Cord Injuries (TSCI), referred to a specialized spine center. SETTING: Patient recruitment and evaluations were conducted at the Brain and Spinal Injury Research Center, Tehran, Iran. METHODS: This study was performed from September 2011 to March 2015 on 1137 consecutive TSCIs. History, clinicoradiological findings as well as chronic complications and social integration were recorded. The capture-recapture method was used to calculate a rough estimation of TSCI prevalence in Tehran Province. RESULTS: Our report includes 1137 cases with a mean age of 29.1 years (s.d.=11.2 year)-79.2% of them being male (M/F=3.8/1). Rough estimation of TSCI prevalence in Tehran province was 2.36 per 10 000 population. Regarding etiology, 61.8% were due to motor vehicle accident (MVA), followed by falling 24.5%, heavy drop 5.2%, violence 3.8%, sport 2.8% and others causes 1.9%. Regarding injury level, 31.5% were cervical, 57.9% thoracic and 10.6% lumbar. Complete lesions were 53.5% of patients and 46.5% were incomplete. Most common neurological type was T1-S5 (American Spinal Injury Association Impairment Scale: A, B, C, 61.7%). Most common complications included urinary tract infection followed by pressure sore (grade III and IV, 37.5%), autonomic dysreflexia (37%) and neuropathic pain (31.2%). Substance abuse was observed in 8.8% of cases. Overall, ~25% in our cases were employed after TSCI. Secondary divorce was also much more frequent than normal matched controls. CONCLUSION: MVA was the most common cause for TSCI. The elderly subjects were less frequent among our patients than more developed countries. The high rate of unemployment and divorce in our cases deserves special consideration.
Subject(s)
Spinal Cord Injuries/epidemiology , Accidents, Traffic , Adolescent , Adult , Age Distribution , Aged , Child , Cross-Sectional Studies , Employment , Female , Humans , Infant , Infant, Newborn , Iran/epidemiology , Male , Middle Aged , Retrospective Studies , Spinal Cord/pathology , Spinal Cord Injuries/complications , Spinal Cord Injuries/etiology , Young AdultABSTRACT
OBJECTIVES: To assess the role of anxiety, depressive mood and religious coping in erectile function among Iranian patients with spinal cord injury (SCI). SETTING: Brain and Spinal Cord Injury Repair Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. METHODS: A sample of N=93 men with SCI participated in this cross-sectional study. Levels of anxiety and depressive mood were assessed using the Hospital Anxiety and Depression Scale. Religious coping strategies were measured using the 14-items Brief Coping Questionnaire. Erectile function was assessed using the International Index of Erectile Function. The joint effect of anxiety, depressive mood and religious coping strategies on erectile function was assessed by performing stepwise multiple linear regression analyses. RESULTS: The mean age of the SCI patients was 37.8 years with a mean post-injury time of 4.6 years. Multivariate regression analyses indicated that age (B=-0.27, 95% CI=-0.47 to -0.07), education (B for higher education=0.63, 95% CI=0.24 to 1.02), the American Spinal Injury Association impairment scale (B for complete impairment=-3.36, 95% CI=-3.82 to -2.89), anxiety (B=-3.56, 95% CI=-5.76 to -1.42), positive religious coping (B=0.30, 95% CI=0.03 to 0.57), negative religious coping (B=-0.56, 95% CI=-0.82 to -0.29) and the duration of injury (B=-0.25, 95% CI=-0.22 to -0.29) were all independent factors influencing erectile function in SCI patients. CONCLUSION: Overall, the results indicated that SCI patients who use positive religious coping strategies had better erectile function compared with individuals who applied negative religious coping strategies. Furthermore, higher levels of anxiety, greater impairment and longer duration of injury turned out to be risk factors for erectile dysfunction.
Subject(s)
Anxiety/etiology , Depression/complications , Erectile Dysfunction/etiology , Religion , Spinal Cord Injuries/complications , Spinal Cord Injuries/psychology , Adaptation, Psychological , Adult , Humans , Iran/epidemiology , Male , Middle Aged , Psychiatric Status Rating Scales , Statistics as Topic , Surveys and Questionnaires , Young AdultABSTRACT
STUDY DESIGN: Prospective study. OBJECTIVES: The objective of this study was to determine whether an integrated and an intensive outpatient program would result in functional improvement of spinal cord injury (SCI) patients with American Spinal Injury Association Impairment Scale (AIS) A injuries as measured by the Spinal Cord Independence Measure (SCIM III). SETTING: Patient recruitment and evaluations were conducted at the Brain and Spinal Injury Repair Research Centre (BASIR), Tehran, Iran. METHODS: Observed SCIM III scores and SCI Ability Realization Measurement Index changes were used to measure the change in 134 patients with complete SCI (AIS A), after participation in an outpatient rehabilitation program consisting of a bimonthly multidisciplinary education program, combined with a twice-weekly occupational therapy, physical therapy and home nursing as a rehabilitation package for a 6-month period. RESULTS: A significant increase in median total SCIM III scores following comparison of 'pre-treatment' scores and final 'post-treatment' scores (9.5 score, P<0.001) was found. The increase in final SCIM III scores was highest in lower cervical (8.75 scores) and thoracic cases (13.5 scores). With the exception of high cervical patients, all subgroups had a significant SCIM III score improvement. CONCLUSION: Multidisciplinary, outpatient rehabilitation programs are recommended as a safe and an effective post-injury rehabilitation for AIS A SCI patients. Such programs may complement inpatient rehabilitation and promote functional recovery. Multidisciplinary outpatient programs are effective in achieving long-term independence in SCI patients and reducing the cost of care for developing countries. This study suggests that high cervical injuries benefit more from inpatient programs.
Subject(s)
Home Nursing/methods , Occupational Therapy/methods , Physical Therapy Modalities , Spinal Cord Injuries/rehabilitation , Treatment Outcome , Adolescent , Adult , Chi-Square Distribution , Chronic Disease , Disability Evaluation , Female , Humans , Iran , Magnetic Resonance Imaging , Male , Middle Aged , Outpatients , Prospective Studies , Rehabilitation Centers/statistics & numerical data , Tomography, X-Ray Computed , Young AdultABSTRACT
OBJECTIVES: We evaluate the level of anxiety and depression among patients with spinal cord injury (SCI) in relation with their religious coping and spiritual health. SETTING: Brain and Spinal Cord Injury Repair Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. METHODS: A sample of patients with SCI participated in this cross-sectional study. They completed a sociodemographic questionnaire, the Hospital Anxiety and Depression Scale, the Brief Religious Coping Questionnaire and the Spiritual Well-being Scale. Then, the association between anxiety, depression and independent variables was examined. RESULTS: In all, 213 patients with SCI were studied. Of these, 64 (30%) have had anxiety and 32 (15%) have had depression. Multiple logistic regression analyses revealed that gender (odds ratio (OR) for female=3.34, 95% confidence interval (CI)=1.31-8.51, P=0.011), employment (OR for unemployed=5.71, 95% CI=1.17-27.78, P=0.031), negative religious coping (OR=1.15, 95% CI=1.04-1.28, P=0.006) and existential spiritual well-being (OR=0.93, 95% CI=0.89-0.97, P=0.003) were significant contributing factors to anxiety (Table 3), whereas negative religious coping (OR=1.21, 95% CI=1.06-1.37, P=0.004) and existential spiritual well-being (OR=0.90, 95% CI=0.84-0.96, P=0.001) were significant contributing factors to depression. CONCLUSION: The findings indicated that depression and anxiety are two psychologically important side effects after SCI. The findings also indicated that religion and spiritual well-being have a moderating role on occurrence of depression and anxiety.
Subject(s)
Adaptation, Psychological/physiology , Anxiety/etiology , Depression/etiology , Religion , Spinal Cord Injuries/complications , Spinal Cord Injuries/psychology , Adult , Cross-Sectional Studies , Female , Humans , Iran , Logistic Models , Male , Middle Aged , Psychiatric Status Rating Scales , Risk Factors , Surveys and Questionnaires , Young AdultABSTRACT
STUDY DESIGN: A randomized, double-blind, placebo-controlled clinical trial. OBJECTIVE: To assess the effect of alpha-lipoic acid (ALA) supplementation on IL-6, hs-CRP, FBS, anthropometric indices, food intake and blood pressure in male patients with chronic spinal cord injury (SCI). SETTING: Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran. METHODS: Fifty-eight men with chronic SCI participated in the study. Participants were divided in two groups: one group received 600 mg of supplemental ALA (n=28) and the other group received placebo (n=30) for 12 weeks. At the beginning and end of the study, biochemical parameters, anthropometric indices, blood pressure and dietary intakes were measured. Dietary intake was measured using N4 software, and statistical analyses were carried out using SPSS16. RESULTS: No significant reduction was found in IL-6 (P=0.97) and hs-CRP levels (P=0.23). There was significant reduction in fasting blood sugar (P=0.001), body weight (P=0.001), BMI (P=0.001), waist circumference (P=0.001) and blood pressure (P=0.001). Dietary intake was significantly reduced, including fat (P=0.001), carbohydrate (P=0.001), protein (P=0.002) and energy intakes (P=0.001). CONCLUSION: Lipoic acid supplementation had no significant effect on the measured inflammatory markers but it reduces fasting blood sugar, anthropometric parameters, food intake and blood pressure in men with chronic SCI.
Subject(s)
Cardiovascular Diseases/diet therapy , Cardiovascular Diseases/etiology , Spinal Cord Injuries/complications , Spinal Cord Injuries/diet therapy , Thioctic Acid/administration & dosage , Vitamin B Complex/administration & dosage , Adult , Anthropometry , Blood Chemical Analysis , Blood Glucose , Blood Pressure/physiology , Body Mass Index , Double-Blind Method , Eating/physiology , Fasting/blood , Humans , Iran , Male , Risk FactorsABSTRACT
Spinal fusion permanently connects two or more vertebrae in spine to improve stability, correct a deformity or reduce pain by immobilizing the vertebrae through pedicle screw fixation. Pedicle screws should be inserted very carefully to prevent possible irrecoverable damages to the spinal cord. Surgeons use CT/fluoroscopic images to find how to insert the screws safely. However, there is still human error, as determining precise trajectory in 3D space is difficult because of asymmetric structure of pedicle. In this study we attempt to propose a shape based method to help the surgeons to find the more accurate and safe path for screw insertion that minimizes the risk or invasiveness of the surgery using pre-operative CT images. We extracted two features for insertion paths from CT images, named "safety margin" and "pedicular screw fixation strength". By using weighted k-means different paths were clustered and compared with each other. Results of comparison between those paths obtained from surgeon's pre-operative planning, intra operative and the proposed method proves a great improvement on the rate of success in reaching a suitable insertion trajectory by using our method. It is observed that the risk of damage in intra operative stage can be potentially high and it can be reduced considerably by using the proposed planning approach.
Subject(s)
Lumbar Vertebrae , Pedicle Screws , Spinal Fusion , Surgery, Computer-Assisted/methods , Tomography, X-Ray Computed/methods , Humans , Lumbar Vertebrae/diagnostic imaging , Lumbar Vertebrae/surgery , Spinal Fusion/instrumentation , Spinal Fusion/methodsABSTRACT
OBJECTIVES: We assess the prevalence of sexual dysfunction in patients with spinal cord injury (SCI), compare sexual function and sexual distress between female patients with SCI and gender-matched healthy controls, and address risk factors associated with sexual dysfunction among Iranian female patients with SCI. SETTING: Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran. METHODS: Eligible Iranian female patients with SCI were included in this cross-sectional study. They were asked to provide sociodemographic information, and complete the Female Sexual Function Index, Hospital Anxiety and Depression Scale and Female Sexual Distress Scale-Revised questionnaire. RESULTS: Of the 105 patients participated in this study, the average age was 41.0 (s.d.=10.1) years. Women with SCI reported significantly higher levels of sexual dysfunction compared with normal controls. Approximately, 88% of SCI patients reported at least one type of sexual dysfunction, whereas only 37% of healthy controls reported sexual dysfunction. Lack of vaginal lubrication was reported more frequent in SCI patients compared with controls. Women with SCI reported a significantly higher level of sexual distress compared with healthy women. Sexual dysfunction was observed to be significantly higher in older patients, those with less education, patients with complete lesions, those with sexual distress and patients who were anxious and depressed. CONCLUSION: Sexual dysfunction is highly prevalent among Iranian women with SCI. Sexual dysfunction is associated with age, education, symptoms of depression and anxiety and level of injury. Sexual counseling during the rehabilitation period may help to prevent sexual dysfunction following SCI.
Subject(s)
Genital Diseases, Female , Spinal Cord Injuries/complications , Spinal Cord Injuries/epidemiology , Adult , Female , Genital Diseases, Female/epidemiology , Genital Diseases, Female/etiology , Genital Diseases, Female/psychology , Humans , Iran/epidemiology , Logistic Models , Middle Aged , Psychiatric Status Rating Scales , Severity of Illness Index , Socioeconomic Factors , Stress, Psychological/epidemiology , Stress, Psychological/etiology , Surveys and Questionnaires , Young AdultABSTRACT
BACKGROUND: Post-traumatic stress disorder (PTSD) is an anxiety disorder that may develop following a trauma. Iranian commercial motor vehicle drivers experience many road traffic accidents during their working life; this may increase the probability for developing PTSD, which in turn may lead to increased human errors as well as decreased work efficiency. OBJECTIVE: To examine the prevalence of PTSD and its associated factors among a group of Iranian commercial motor vehicle drivers. METHODS: In a cross-sectional study, 424 drivers who referred to participate in an annually training program were selected using a simple random sampling technique. They were requested to complete the Persian version of PCL-C and a data collection sheet about their occupational and demographic features. RESULTS: 385 (90.8%) of 424 studied drivers completed the study. 265 (68.8%) of the drivers had first-grade driving license. The mean±SD on-the-job daily driving was 10.2±2.8 h. 74 of 385 (19.2%; 95% CI: 15.3%-23.2%) met the PTSD criteria. Higher age and job experience as a professional driver, and having past history or past familial history of psychiatric disorders, were independent predictors of developing PTSD. The disease was more prevalent among drivers with first-grade driving license. CONCLUSION: The prevalence of PTSD among Iranian commercial motor vehicle drivers is higher than the figures reported elsewhere. Measures to diagnose of such drivers and to ensure optimum follow-up of victims before return to professional driving should be considered.
Subject(s)
Accidents, Occupational , Accidents, Traffic , Automobile Driving , Stress Disorders, Post-Traumatic/epidemiology , Accidents, Occupational/psychology , Accidents, Occupational/statistics & numerical data , Accidents, Traffic/psychology , Accidents, Traffic/statistics & numerical data , Adult , Automobile Driving/psychology , Automobile Driving/statistics & numerical data , Cross-Sectional Studies , Humans , Iran/epidemiology , Male , Middle Aged , Occupational Health , PrevalenceABSTRACT
To investigate the effects of silymarin on follicular development, we enrolled 40 healthy women undergoingin vitro fertilization (IVF) due to male factor infertility in this trial. They underwent ovulation induction and on a random and blind basis, patients were assigned to receive silymarin (70 mg x 3/day) or placebo from the beginning of the induction cycle. The number and quality of oocytes retrieved were evaluated and apoptosis of > or = granolusa cells was studied. There was no significant difference between the groups for mean number of follicles 18 mm (P = 0.131), mean number of oocytes retrieved (P = 0.209) or endometrial thickness (P = 0.673). However, the proportion of total apoptosis in the study group was significantly lower than in the placebo group (P = 0.032). These data suggest that administration of silymarin in IVF patients concomitantly with gonadotropin results in reduction of granolusa cell apoptosis but does not have any effect in promotion of follicular development, oocyte retrieval or endometrial thickness.
Subject(s)
Antioxidants/therapeutic use , Apoptosis/drug effects , Fertilization in Vitro/methods , Granulosa Cells/drug effects , Ovarian Follicle/drug effects , Silymarin/therapeutic use , Adult , Antioxidants/pharmacology , Chorionic Gonadotropin/therapeutic use , Drug Therapy, Combination , Endometrium/diagnostic imaging , Endometrium/drug effects , Female , Humans , Infertility, Male/therapy , Iran/epidemiology , Male , Ovarian Follicle/diagnostic imaging , Ovarian Follicle/growth & development , Pregnancy , Reproductive Control Agents/therapeutic use , Silymarin/pharmacology , Single-Blind Method , Treatment Outcome , UltrasonographyABSTRACT
To investigate the effects of silymarin on follicular development, we enrolled 40 healthy women undergoing in vitro fertilization [IVF] due to male factor infertility in this trial. They underwent ovulation induction and on a random and blind basis, patients were assigned to receive silymarin [70 mg X 3/day] or placebo from the beginning of the induction cycle. The number and quality of oocytes retrieved were evaluated and apoptosis of granolusa cells was studied. There was no significant difference between the groups for mean number of follicles >/= 18 mm [P = 0.131], mean number of oocytes retrieved [P = 0.209] or endometrial thickness [P = 0.673]. However, the proportion of total apoptosis in the study group was significantly lower than in the placebo group [P = 0.032]. These data suggest that administration of silymarin in IVF patients concomitantly with gonadotropin results in reduction of granolusa cell apoptosis but does not have any effect in promotion of follicular development, oocyte retrieval or endometrial thickness
Subject(s)
Silymarin , Ovulation Induction , Apoptosis , Oocytes , Fertilization in Vitro , Granulosa CellsABSTRACT
BACKGROUND AND AIMS: The lack of knowledge about key traits in field environments is a major constraint to germplasm improvement and crop management because waterlogging-prone environments are highly diverse and complex, and the mechanisms of tolerance to waterlogging include a large range of traits. A model is proposed that waterlogging tolerance is a product of tolerance to anaerobiosis and high microelement concentrations. This is further evaluated with the aim of prioritizing traits required for waterlogging tolerance of wheat in the field. METHODS: Waterlogging tolerance mechanisms of wheat are evaluated in a range of diverse environments through a review of past research in Australia and India; this includes selected soils and plant data, including plant growth under waterlogged and drained conditions in different environments. Measurements focus on changes in redox potential and concentrations of diverse elements in soils and plants during waterlogging. KEY RESULTS: (a) Waterlogging tolerance of wheat in one location often does not relate to another, and (b) element toxicities are often a major constraint in waterlogged environments. Important element toxicities in different soils during waterlogging include Mn, Fe, Na, Al and B. This is the first time that Al and B toxicities have been indicated for wheat in waterlogged soils in India. These results support and extend the well-known interactions of salinity/Na and waterlogging/hypoxia tolerance. CONCLUSIONS: Diverse element toxicities (or deficiencies) that are exacerbated during waterlogging are proposed as a major reason why waterlogging tolerance at one site is often not replicated at another. Recommendations for germplasm improvement for waterlogging tolerance include use of inductively coupled plasma analyses of soils and plants.
Subject(s)
Adaptation, Physiological , Elements , Floods , Soil , Triticum/growth & development , Triticum/physiology , Adaptation, Physiological/drug effects , Aerobiosis/drug effects , Aluminum/toxicity , Anaerobiosis/drug effects , Analysis of Variance , Australia , Biomass , Environment , Genetic Variation , India , Models, Biological , Oxidation-Reduction/drug effects , Plant Leaves/drug effects , Plant Leaves/metabolism , Plant Shoots/growth & development , Plant Shoots/metabolism , Triticum/drug effects , Triticum/geneticsABSTRACT
The brain response to temporal frequency (TF) variation has already been reported, but with no study for different TF with respect to various spatial frequencies (SF). Functional magnetic resonance imaging (fMRI) was performed with a 1.5 Tesla General Electric system in 14 volunteers during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.4 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block-designed fMRI study. Voxels whose Z value was above a threshold of 3.0, at a significance level P = 0.05, were considered activated. The results demonstrated that the percentage BOLD signal change in response to different TFs was the maximum value at 6 Hz for a high SF of 8 cpd, whereas it was the maximum at TF of 8 Hz for a low SF of 0.4 cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of amblyopia) and selecting a visual task in fMRI studies.
Subject(s)
Visual Cortex/physiology , Visual Perception/physiology , Adult , Female , Humans , Magnetic Resonance Imaging , MaleABSTRACT
The brain response to temporal frequencies (TF) has been already reported, but with no study for different TFs with respect to various spatial frequencies (SF). Functional Magnetic Resonance Imaging (fMRI) experiments were performed by 1.5 Tesla General Electric-system in 14 volunteers (9 males and 5 females, range 19-26 years) during square-wave reversal checkerboard visual stimulation with different temporal frequencies of 4, 6, 8 and 10 Hz in two states of low SF of 0.5 and high SF of 8 cpd (cycles/degree). The activation map was created using the data obtained from the block designed fMRI study. Pixels whose correlation coefficient value was above a threshold of 0.33, in significant level P<0.01 were considered activated. The average percentage BOLD (blood oxygenation level dependent) signal change for all activated pixels within the occipital lobe, multiplied by the total number of activated pixels within the occipital lobe, was used as the criterion for the strength of the fMRI signal at each state of TF&SF. The results demonstrated that the strength of the fMRI signal in response to different TFs was maximum in 6Hz for high SF of 8 cpd, while it was maximum at TF of 8Hz for low SF of 0.5 cpd. The results of this study agree with the results of animal invasive neurophysiological studies showing spatial and temporal frequency selectivity of neurons in visual cortical areas. These results can be useful for vision therapy (such as the treatment of Amblyopia) and selecting visual task in fMRI studies.
Subject(s)
Brain Mapping/methods , Evoked Potentials, Visual/physiology , Magnetic Resonance Imaging/methods , Photic Stimulation/methods , Space Perception/physiology , Visual Cortex/physiology , Adaptation, Physiological/physiology , Adult , Female , Humans , MaleABSTRACT
The brain response to temporal frequencies (TF) has been already reported, but with no study for different TF in respect to various spatial frequencies (SF). fMRI was performed by 1.5T GE-system in 14 volunteers during checkerboard visual stimulation, with TFs of 4, 6, 8 and 10Hz in low and high SFs of 0.5 and 8cpd. The averaged percentage BOLD signal changes demonstrated the amplitude of the fMRI response to different TFs which was maximally at 6Hz for high SF of 8cpd, and at 8Hz for low SF of 0.5cpd. The results are useful for vision therapy (such as the treatment of Amblyopia) and for fMRI applications incorporating visual tasks.